The preparation of polymerizable multi-component compositions, such as those used in orthopaedic and dental applications, is typically a two-step process. First, individual components are thoroughly mixed, for example, by stirring or simultaneous expression through a mixing device. After mixing, the resulting composition is loaded into a system for delivery of the material to the desired location. These compositions include, for example, poly (methylmethacrylate)-based compositions, as well as compositions of the type described in U.S. Pat. Nos. 5,681,872 and 5,914,356, assigned to the assignee of the present application and incorporated herein by reference in their entireties.
For some polymerizable compositions, the individual components are viscous pastes. Upon mixing, the viscosity of the resulting composition increases as the material polymerizes and sets. Working time—the amount of time before the composition becomes too viscous or rigid to be manipulated—is generally about five to eight minutes, depending on the composition. As such, the user must work expeditiously to quickly mix the components, load the composition into the delivery system, and deliver the composition to the situs, before the working time expires. Moreover, and especially in procedures where the composition is delivered within intraosseous spaces, the delivery of the composition must be extensively supervised; if the composition leaks out of the situs, numerous complications, including death, can result. Some of the working time is thus sacrificed to order to ensure the safe delivery of the compositions. Methods, devices, and kits have been developed to facilitate the mixing of the individual components, e.g., U.S. Pat. Nos. 6,375,659, 6,800,245, and 6,613,018, all assigned to the assignee of the present application and incorporated herein by reference, in their entireties.
In addition, the highly viscous quality of these materials complicates delivery as high pressures are required to express the materials from delivery devices currently used. Current delivery devices use syringe-type devices requiring manual exertion against a plunger-type device. Manual exertion makes it difficult for the user to express controlled volumes of the compositions. Moreover, as the delivery is monitored, the user may desire to stop the expression of the composition and observe whether any seepage or leaking of the material has occurred. The highly viscous quality of the materials hinders the ability to timely stop and resume delivery.
Currently, precious minutes of working time are consumed by the mixing of the components and loading of the composition into a delivery device. Thus, there is a need for devices that minimize the time between the mixing of the components and the delivery of the compositions to the situs. Additionally, there remains a need to deliver these highly viscous compositions with greater control.